By James Cormack While multiple teams have claimed four trophies in a single season, only one can truly say they completed the ultimate quadruple. The legendary vintage of Jock Stein’s 1966/67 Celtic can get lost in the sands of time, but the homegrown Lisbon Lions were one of a kind. While Pep Guardiola’s Barcelona and Hansi Flick’s Bayern Munich can each claim their respective places in history with unofficial quadruples, Stein’s Celtic effectively completed the sport after downing catenaccio adorers Inter in the 1967 European Cup final. A come-from-behind triumph in Lisbon meant Celtic had …